On Saturday 06 November 2010 13:30:45, C K Kashyap wrote:
Hi, I was trying to put a String in a ByteString
import qualified Data.ByteString.Lazy as BS message :: BS.ByteString message = runPut $ do let string="SOME STRING" map (putWord8.fromIntegral.ord) string -- this ofcourse generates [Put]
You'd want mapM_ (putWord8 . fromIntegral . ord)
How can I convert the list of Put's such that it could be used in the Put monad?
sequence_ :: Monad m => [m a] -> m () if you want to use the results of the monadic actions, sequence :: Monad m => [m a] -> m [a] Often sequence and sequence_ are used for list resulting from a map, so there's mapM_ :: Monad m => (a -> m b) -> [a] -> m () mapM_ f xs = sequence_ (map f xs) mapM :: Monad m => (a -> m b) -> [a] -> m [b] mapM f xs = sequence (map f xs)
For now I used the workaround of first converting the string to ByteString like this -
stringToByteString :: String -> BS.ByteString stringToByteString str = BS.pack (map (fromIntegral.ord) str)
and then using putLazyByteString inside the Put monad.